A new united atom potential model was developed for the vapor-liquid phase equilibrium of alpha-olefins ranging from l-butene to 1-octene. The vapor pressure, normal boiling point, second virial coefficient, heat of vaporization, and structure were calculated with the new model, over a wide temperature range, and compared to experimental data. Critical constants of purl components were reproduced satisfactorily. Furthermore, this model was used to calculate the 1-butene-n-hexatriacontane and 1-hexene-n-hexatriacontane mixture phase equilibria at high pressure. Pressure-composition phase diagrams and lower critical solution temperature curves were constructed and compared to limited literature experimental data and predictions from an equation of state.